Theory of double excitation and ionization by a strong pulsed laser: Application to atomic carbon

We present a theory and calculations for double ionization of atomic carbon by a pulsed strong laser of intensity up to 10¹⁴ W/cm². Up to five-photon ionization is included in a formalism that accounts for the modification of doubly excited states by the laser field. Sequential and direct double ionization are calculated, as are excited ionic states and their role in the possibility of creation of inverted ionic populations.